A gene mutation is a permanent alteration in the DNA sequence that makes up a gene, such that the sequence differs from what is found in the original sequence. Mutations range in size; they can affect a single nitrogen base in a DNA molecule to a large segment of a chromosome that includes multiple genes. We know that DNA replication occurs before both mitosis and meiosis. Explain how a mutation can and cannot be passed to offspring through these processes.

Question

A gene mutation is a permanent alteration in the DNA sequence that makes up a gene, such that the sequence differs from what is found in the original sequence. Mutations range in size; they can affect a single nitrogen base in a DNA molecule to a large segment of a chromosome that includes multiple genes. We know that DNA replication occurs before both mitosis and meiosis. Explain how a mutation can and cannot be passed to offspring through these processes.

Answer 1

A mutation can be passed to offspring through both mitosis and meiosis, but the extent of its inheritance differs between the two processes.

During mitosis, a type of cell division that leads to the production of identical daughter cells, a mutation can be passed to all daughter cells that arise from the mutated cell. This means that if a mutation occurs in a somatic (non-reproductive) cell during mitosis, it will not be passed on to offspring since somatic cells do not directly contribute to the development of offspring. However, if a mutation occurs in a germ cell, which gives rise to eggs or sperm, during mitosis, it can be passed on to the offspring. The mutated germ cell will undergo meiosis to produce gametes (egg or sperm), which will contain the mutation. When these gametes combine during fertilization to form a zygote, the mutation will be present in the offspring's DNA.

During meiosis, the process by which germ cells divide to form eggs or sperm, a mutation can also be passed to offspring. Meiosis involves two rounds of cell division, resulting in the production of four haploid cells (gametes), each with half the number of chromosomes as the parent cell. If a mutation occurs in one of the germ cells before meiosis, it will be present in all four gametes produced by that germ cell. These mutated gametes can then be used for fertilization, resulting in offspring with the mutation. However, if a mutation occurs after meiosis has already taken place, it will not be passed on to offspring.

In summary, mutations that occur in germ cells during either mitosis or meiosis have the potential to be passed on to offspring. Mutations in somatic cells during mitosis will not be transmitted to offspring.